The company, which is part of the giant Associated British Foods group, said it was proposed that both factories would close in spring 2008.

A 90-day period of consultation is underway with workers.

Mr Mayhew added: "It in no way reflects the commitment and effort of our teams at both sites.

"However, the reality is that we can only sustain our business in the longer term by moving to a lower cost manufacturing operation with more flexibility to make a wider range of products than our current factories will allow."

He said the company intended to do "everything possible" to minimise the impact on workers.